1. Field of the Invention
The present invention relates to a lamp for vehicle, and more particularly, to a structure for sealing a space between a front lens and a lamp body of the lamp for the vehicle.
2. Prior Art
In general, a lamp for a vehicle is structured such that when joining a front lens to the lamp body, a sealing member is interposed therebetween to maintain a required sealing efficiency between the lamp body and the front lens so as to prevent introduction of water, dust or the like into the interior of the lamp.
Hitherto, as the sealing member, a hot melt 114A as shown in FIG. 7(a), an elastic cord 114B as shown in FIG. 8(b), and a foamed gasket 114C as shown in FIG. 9(b) have been known.
The hot melt 114A is a thermoplastic adhesive having great adhesive strength and generating no repulsion force. Therefore, when a front lens 116 is secured to a lamp body 112, a strong mechanical joining, for example, by using threaded fasteners such as screws, is not required. That is, the hot melt 114A has an advantage that allows the usage of only engagement fastening as an effective means of mechanical joining. There, however, arises the following problem when the components of the lamp are intended to be recycled. That is, the hot melt 114A having the great adhesive strength inhibits easy separation of the front lens 116 from the lamp body 112. If the separation is forcibly performed, a cohesion failure (a phenomenon in which the structure of the hot melt 114A is torn along random surfaces of breakage) occurs as shown in FIG. 7(b) . Therefore, not only the hot melt 114A encounters cohesion failure, but also the lamp body 112, and a front lens 116 to which a chip of the hot melt 114A is still adhered cannot be recycled.
Regarding FIGS. 8(a) and 9(a), the elastic cord 114B and the foamed gasket 114C are made of a thermosetting elastic material having no tackiness. Therefore, the front lens 116 can be attached to or detached from the lamp body 112 without elastic cord residue, allowing recycling of the lamp components. However, each of the elastic cord 114B and the foamed gasket 114C yields a great elastic repulsion force so as to maintain sealing efficiency. Therefore, as shown in FIGS. 8(b) and 9(b), the repulsion force constantly acts on the front lens 116 so as to be forced out. Therefore, simple fastening means such as engagement fasteners are insufficient as the mechanical fastening means for securing the front lens 116 to the lamp body 112. Thus, strong fastening means such as threaded fasteners have to be additionally used as shown in FIG. 10 (referring to the drawing, the symbol A represents engagement fastening portions and B represents threaded fasteners). As a result, the structure of the lamp becomes too complicated to improve workability in the process for assembling the lamp. In these foregoing cases, the elastic repulsion force also frequently causes failure such as deformation or a fracture of the front lens 116.
Since the elastic cord 114B is a complete product serving as the elastic sealing member, it is difficult to apply the elastic cord 114B automatically to the sealing position on the lamp body 112. Therefore, the elastic cord 114B is applied by performing a manual bonding operation. As a result, there arises a problem of deteriorated workability in the process for assembling the lamp. As for the foamed gasket 114C, the foamed gasket material can be automatically applied to the sealing position on the lamp body 112. However, hardening of the applied foamed gasket material takes a long time. Also in this case, there arises the problem of deteriorated workability in the process for assembling the lamp.